Quantum Chemistry / DFT
Molecular structure / Affinity / Solubility
Materials Science
Life Science

[Analysis Example] Evaluation of van der Waals Functionals of SIESTA

Test results of VDW functionals implemented in SIESTA

Objectives and Methods

The DFT software SIESTA allows the calculation of interactions taking into account intermolecular forces. Here we present test results for various van der Waals functionals implemented in SIESTA for the interaction energy between two molecules, known as the S22 Benchmark set[1].

Figure 1.  22 molecular pairs used for benchmarking
Figure 1. 22 molecular pairs used for benchmarking


The following are the results of the S22 benchmark test using the VDW functionals implemented in SIESTA, DRSLL[2], LMKLL[3], KBM[4], C09[5], BH[6], and VV[7], and the PBE-D functional with Grimme's dispersion power correction[8].

The basis function was DZP (Double-Zeta+Polarization) and the interaction energy with Counterpoise correction was compared to the reference value (CCSD(T)/CBS CP).

Errors with the reference value were calculated. The standard deviation of absolute error (SDEV) and mean squared error (MAE) were used to evaluate each category of A, B, and C. The results are shown in Figure 2.

Figure 2. S22 benchmark test results Figure 2. S22 benchmark test results

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